1. Field of the Invention
The present invention relates to a vacuum insulated switch and a vacuum insulated switchgear, and particularly to a double-break three-position vacuum insulated switch having circuit breaker and disconnector functions and a vacuum insulated switchgear using such a switch.
2. Description of Related Art
Today, in the field of power receiving and transforming systems, user needs are diversified. Each user system uses a different load type and operating condition depending on the application, and each local electricity distribution system is designed by considering the safety, reliability, maintenance and future load requirement. There also need to be considered devices for controlling the breaker, disconnector, and grounding switch of the power receiving and transforming system, as well as devices for monitoring and measuring the system parameters such as voltage, current and power.
An important consideration in such design is how to minimize the space required for installation of the above-cited various devices and how to reduce the installation cost. A solution to this problem is a double-break three-position vacuum switch (e.g., JP2007-14086A).
This double-break three-position vacuum switch contains: in a vacuum container therein having insulating cylinders, two stationary contacts; and two movable contacts capable of contacting and separating from the respective stationary contacts, thereby providing a double-break configuration. The two movable contacts are connected by a movable conductor, which is further connected to a vacuum insulated actuating rod. The vacuum insulated actuating rod extends outside the vacuum container via a metal bellows and is then connected to an operating rod guided by a guide. The operating rod is further connected to an operating lever, which is operated by an operating device. A rotary motion of the operating lever caused by the operating device is converted to a linear motion of the operating rod and vacuum insulated actuating rod. And the movable contacts can be held at three different positions: a closed position to permit current flow; an open position to interrupt current flow; and a disconnect position to ensure the safety of inspection personnel against a surge voltage such as lightning.    Patent document 1: Japanese Patent Application Laid-open No. 2007-14086 (paragraphs 0024-0030 and FIG. 5).